public void AddStringElementToArray() { // Arrange var document = new JsonDocument(@"{ 'a': { 'x': '1' }, 'b': '2', 'c': '3', 'd': [] }"); // Act document.AddElementToArray(new[] { "d" }, "1"); var result = document.ToString(); // Assert Assert.Equal(@"{ ""a"": { ""x"": ""1"" }, ""b"": ""2"", ""c"": ""3"", ""d"": [ ""1"" ] }", result, ignoreCase: true, ignoreLineEndingDifferences: true, ignoreWhiteSpaceDifferences: true); }